Smoking article

Abstract

The present invention relates to smoking articles, for example electronic cigarettes (h referred to as “e-cigarettes”), and fluid reservoirs for use therewith or therein.

Claims

1. A smoking article comprising: a housing; a heating element; a power source for at least the heating element; a fluid reservoir; and a wicking element which transfers fluid from the fluid reservoir to the heating element; wherein the fluid reservoir comprises an element comprising a plurality of bicomponent fibres and a fluid; and wherein the bicomponent fibers have a bonded fibre density of about 0.05 to 0.50 g/cc.

2. The smoking article according to claim 1, which is an electronic cigarette (e-cig or e-cigarette), personal vaporizer (PV) or electronic nicotine delivery system (ENDS).

3. A smoking article according to claim 1 wherein the heating element comprises a resistance wire of resistance 2.20 to 2.5 Ω, the resistance wire being formed as a coil or helix having 6 to 8 turns.

4. A smoking article comprising: a housing; a heating element; a power source for at least the heating element; a fluid reservoir; and a wicking element which transfers fluid from the fluid reservoir to the heating element; wherein the fluid reservoir comprises a longitudinally extending tubular element comprising a plurality of bicomponent fibres and a fluid; and wherein the bicomponent fibers have a bonded fibre density of about 0.05 to 0.50 g/cc and a fluid.

5. The smoking article according to claim 4, which is an electronic cigarette (e-cig or e-cigarette), personal vaporizer (PV) or electronic nicotine delivery system (ENDS).

Description

(1) The present invention will now be illustrated with reference to the following Examples and the attached drawings in which FIG. 1 schematically illustrates (not to scale) a reservoir according to an example of the invention; and FIG. 2 shows a simplified exploded view of an e-cigarette according to an example of the invention (including a reservoir according to an example of the invention).

(2) FIG. 1 shows a fluid reservoir 12 according to an example of the invention. The reservoir 12 comprises a longitudinally extending tubular element 20 of length 33 mm which has an annular cross section (of outer diameter 7.5 mm and inner diameter 4.25 mm, and which is formed from a plurality of bicomponent fibres. The bicomponent fibres which form the tubular element define a (single) hollow cylindrical channel 21 of circular cross section (and diameter 4.25 mm) which extends longitudinally through the element. Element 20 has a uniform cross section, so it will be appreciated that the (single) hollow cylindrical channel 21 of circular cross section extends the full length of tubular element 20.

(3) The tubular element 20 is formed using the process described in U.S. Pat. No. 5,607,766. A plurality of bicomponent fibres having a polypropylene core surrounded by a sheath of polyethylene terephthalate was made using melt blown bicomponent technology. This web was formed into tubular rod using apparatus similar to that known for the manufacture of plasticized cellulose acetate cigarette filter elements. The tubular rod so produced was cut into discrete multiple product rods, which were then each cut into individual tubular elements 20 of 33 mm length.

(4) The mean weight of tubular element 20 is 0.205 g. This gives a bonded fibre density in the longitudinally extending tubular element 20 of 0.21 g/cc. It will, of course, be appreciated that it is possible to adjust weight and density to meet requirements, e.g. for an element with a reduced pressure drop.

(5) The tubular element 20 was loaded with a fluid (e-liquid) in the form of 1.2 g propylene glycol with a nicotine content of 2%.

(6) FIG. 2 shows a simplified exploded view of an electronic cigarette according to the invention including a reservoir 12 according to the invention. The illustrated construction—of a one-part disposable device—is fairly generic and numerous examples of products with the same basic construction are known in the prior art.

(7) The e-cigarette device is enclosed within a housing, tubular body 1. As seen in FIG. 2, at one end (the upstream end) of the tubular body 1, there is an LED end cap 2 that lights up when a flow sensor 3 (located immediately downstream of the end cap 2 within annular silicone cap 4) detects that a user is drawing on the downstream (mouth) end of the tubular body. A 3.7 V cylindrical lithium ion battery 5, located downstream of the sensor 3 and cap 4, powers the device and there is a cylindrical battery seal 6 downstream of the battery 5. Downstream of battery seal 6, a heater (heating element) 8 is contained and protected within a tubular fibreglass sleeve 9. A wick (wicking element) 10 of e.g. cotton passes through holes in sleeve 9, and the tubular sleeve 9 and wick 10 are surrounded by a tubular reservoir 12 of the invention, the sleeve described above with reference to FIG. 1. It will be appreciated that when the e-cigarette device is assembled the reservoir 12 surrounds and encloses the tubular sleeve 9 and the heater 8 located therein, with the wick extending through holes in the sleeve 9 so the wick is in contact with both the heater 8 (within sleeve 9 ) and the surrounding reservoir 12. It will also be appreciated that the dimensions, particularly the inner and outer diameters of the tubular reservoir 12, are selected so tubular sleeve 9 and wick 10 (and sleeve 11 if present) fit snugly within the cavity of the reservoir 12, and the reservoir 12 fits snugly within the housing body 1. The reservoir 12, which is porous, holds the e-liquid. In some embodiments there may be a further cotton sleeve 11 situated between reservoir 12 and sleeve 9, but this is optional (although shown in FIG. 2). Downstream of the reservoir 12/tubular sleeve 9/heater 8 assembly, a further seal 7 is provided, together with an end cap 13 at the mouth end for hygiene and convenience.

(8) In use, as is well known, the user draws on the product (on mouth end cap 13 ) and the heater is activated by the sensor 3. Air enters the device through the end cap 2 and holes in tube 1. E-liquid is transferred from the reservoir 12 to heater 8 by wicking over or through wick (wicking element) 10, where it is vaporised and delivered to the consumer.

(9) The prior art device used a wrapped nonwoven batt as the reservoir. According to the invention, the use of reservoir 12, which comprises bicomponent fibres, provides significant advantages in terms of vapour and nicotine delivery, as illustrated below.

EXAMPLE 1

(10) E-cigarettes of a market-leading disposable type (herein after called ‘A’) were purchased and compared to those of the invention (hereinafter called ‘B’). Both products were of the same dimensions and used comparable components (other than the reservoir) wherever possible. Cotton sleeve 11 was omitted from device B. The reservoir of the e-cigarette according to the invention had an outer diameter of 7.5 mm, an inner diameter of 4.25 mm, length 33 mm and weight 0.205 g (which gives a bonded fibre density of 0.21 g/cc, as set out above). It was loaded with 1.2 g propylene glycol with a nicotine content of 2% (e-liquid). This e-liquid was similar to our analysis of the e-liquid used in prior art device A, which featured a conventional rolled nonwoven batt reservoir. These two products were then analysed on a standard smoking machine using 55 ml square wave puff of 3 sec duration, taken at 2 puffs per minute. The vapour was collected for puffs 1-40, 41-80, 81-120. 121-160, 161-200 and 201-240. It is considered that 240 puffs is the typical maximum number of puffs consumers would take from disposable e-cigarettes before the device is exhausted. Consumers are likely to be dissatisfied if the device did not last 240 puffs.

(11) The table below gives the mean total vapour and total nicotine delivered over the puff numbers in question. The mean values are based on smoking of 20 devices of each type and the co-efficient of variation of these means is also quoted. Clearly a lower CV is preferred as this provides a more consistent experience to the consumer.

(12) TABLE-US-00001 Prod- Measure- Puff Numbers uct ment 1-40 41-80 81-120 121-160 161-200 201-240 A Vapour 66.2 56.5 50.7 45.3 37.9 28.9 Delivery (mg) Vapour 41.0 40.3 39.5 42.3 48.5 55.3 CV (%) Nicotine 1.04 0.96 0.89 0.78 0.68 0.56 Delivery (mg) Nicotine 42.8 36.5 34.6 43.3 46.0 41.7 CV (%) B Vapour 105.9 86.9 77.1 69.3 63.2 51.3 Delivery (mg) Vapour 38.3 36.4 36.3 37.6 38.2 40.2 CV (%) Nicotine 1.87 1.53 1.36 1.23 1.15 0.93 Delivery (mg) Nicotine 32.1 33.6 34.9 35.6 35.8 41.9 CV (%)
It can be seen that device B of the invention advantageously provides both greater vapour delivery (average increase 50%) and greater nicotine delivery (average increase 65%), with less variability (typically 13-14% less) than market-leading conventional device A.

(13) The applicants have also developed an improved heater, which may be used as heater element 8 in the e-cigarette device shown in FIG. 2. The 3.7 V lithium ion battery 5 is used in conjunction with a 35 mm length of 0.142 mm thick nickel chromium wire (resistance 68Ω/m, giving a total resistance of 2.38 Ω) to provide enhanced vapour delivery and improved device performance. The nickel chrome wire is coiled around a 1.5 mm fibreglass silica material with a total of 7 windings to form the heating element. This combination of battery voltage, wire rating resistance and coil setup provide an optimised power output between the maximum and minimum output voltages (4.2 V-3.4 V), before the battery is exhausted, together with improved surface contact between the wire and wicking material. Power outputs between 7.41 watts and 4.86 watts are known to provide optimal vapour creation and nicotine delivery without burning the liquid or becoming incapable of providing enough power to generate vapour. Using this improved power source, device B had a power output of 5.75 W at a voltage of 3.7 V, within this optimum range. The applicants found that 7 windings provides a high surface contact area with the wick to generate high vapour output (e.g. in comparison to device A). Earlier samples using lower resistance wire were shown to generate excessive heat, thereby causing the liquid to burn and the device housing to become hot to the touch.

EXAMPLE 1A

(14) The extraction efficiency of the reservoir of the invention was compared with that for competitor reservoirs, which do not comprise a porous element comprising a plurality of bicomponent fibres. As for example 1, the reservoir of the e-cigarette according to the invention had an outer diameter of 7.5 mm, an inner diameter of 4.25 mm, length 33 mm and weight 0.205 g (which gives bicomponent fibres having a bonded fibre density of 0.21 g/cc, as set out above). The reservoir of the invention and the two competitor products were loaded with e-liquid (same as for Example 1), with the volume set out in Table 2 below. The products were then analysed on a standard smoking machine using 55 ml square wave puff of 3 sec duration, taken at 2 puffs per minute.

(15) The liquid retention after the test is shown in Table 2 below. It can be seen that the reservoir of the invention provides: (i) higher TPM delivery over the first 40 puffs (160 mg vs 83 mg vs 52 mg); and (ii) average “Post Vape Liquid Retention” of 22.24% vs. comparatives of 55.28% and 66.92%. This is indicative of high extraction efficiency from the reservoir of the invention.

(16) TABLE-US-00002 TABLE 2 Mean TPM Reservoir Fill delivery Device density, volume, Liquid retention post vape, % over initial Tested g/cc Material ml MIN MEAN MAX SD CV(%) 40 puffs, mg Invention 0.21 Polyester 1 16.62 22.24 28.92 3.63 16.34 160 Competitor 1 0.21 Polyester 1.1 44.43 55.28 72.88 10.69 19.33 83 Competitor 2 0.2 Polyester 0.6 37.42 61.92 81.50 15.93 25.73 52